|
Search: id:A052731
|
|
|
| A052731 |
|
A simple context-free grammar in a labeled universe. |
|
+0
1
|
|
| 0, 0, 0, 6, 48, 600, 8640, 151200, 3064320, 71124480, 1857945600, 54007430400, 1729195776000, 60483053030400, 2294881337548800, 93889711948032000, 4120492394962944000, 193100926276177920000, 9624765220305371136000
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 687
|
|
FORMULA
|
E.g.f.: (1/2)/x*(1-x-(1-2*x-3*x^2)^(1/2))-1/2-1/2*x+1/2*(1-2*x-3*x^2)^(1/2)
Recurrence: {a(1)=0, a(2)=0, a(3)=6, (-15*n+15*n^3+15*n^2+3*n^4-18)*a(n)+(-n^3-7*n^2-16*n-12)*a(n+1)+(-3*n^2-16*n-21)*a(n+2)+(n+4)*a(n+3), a(4)=48, a(5)=600}
|
|
MAPLE
|
spec := [S, {C=Prod(B, Z), S=Prod(B, C), B=Union(S, Z, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A052567 A002170 A153467 this_sequence A052711 A113388 A113393
Adjacent sequences: A052728 A052729 A052730 this_sequence A052732 A052733 A052734
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
